The present invention relates to heavy duty under lifts used for buses, coaches, trucks or tractors, for example.
Vehicle recovery has successfully developed damage-free towing operations utilizing, for example, wheel lifts such as those described in U.S. Pat. Nos. 4,836,737 and 4,798,509. Such lifting apparatus is not suitable for the recovery of heavy vehicles such as buses, coaches (motorhomes, large recreational vehicles), large trucks or tractors.
Heavy duty wheel lifts are available. However, these are fairly time-consuming to hook-up. Also, special installation is required for their use, and towers may not desire this.
Heavy-duty recovery vehicles may be called upon to lift and tow Class 7 (26,000-33,000 pounds) and Class 8 (over 33,000 pounds) disabled vehicles. For certain towing operations, such underlift vehicles may be outfitted with heavy duty wheel lifts. Large vehicle recovery trucks known as heavy-duty “underlifts” have been developed for towing heavy vehicles, such as the Challenger Heavy Duty Series underlift 10 available from Miller Industries and shown in FIG. 16 (although the lift adaptor 20 is part of the present invention and is not prior art). These underlifts have rugged, heavy-duty wheel lifts or underlifts which may be fitted with forks or other apparatus for towing applications.
The towing of heavy vehicles using underlifts has long suffered from several problems. Towing of such vehicles is commonly prefaced by pre-picking them. “Pre-picking” involves extending the underlift of the towing vehicle, initially without the use of forks, and picking up the vehicle on the bottom of its front or rear axle, engine frame, floor pan or cross members. Because these items may be offset to one side, pre-picking usually does not result in an even lift. Once lifting has been accomplished in this fashion, wooden blocking is placed under the tires of the vehicle to be towed. Blocked, the towed unit is at a sufficient height to allow the underlift, now fitted with forks, to be engaged for towing. However, the use of wooden blocking is a safety issue, as the towed vehicle can roll or slide off the blocking. Underlift forking may damage the air bags, air dryers, suspension parts, engine, coolant lines, transmission, wheel chair access mechanisms, etc., of the towed vehicle. Thus, pre-picking can be a time-consuming and labor-intensive operation, and may also result in damage to fragile suspension parts of the towed vehicle.
In addition to these problems, excessive hook-up time may jeopardize safety, and the use of existing heavy duty underlifts can result in excessive overhang. Given the disabled vehicle weights involved, a substantial overhang, such as much as 18 feet, may occur when lifting and towing heavy vehicles. In addition, as overhang increases towed vehicle turning can result in overswing into an adjacent lane(s) occurs.
Accordingly, there is a need in the heavy-duty vehicle towing field for apparatus facilitating the safe and efficient hook-up and towing of heavy vehicles such as buses, coaches, trucks and tractors that eliminates the problem of excessive overhang, speeds hook-up times, provides safer working conditions, and minimizes damage to the towed vehicle, as compared to the use of current, heavy-duty wheel lift and underlift systems.